• Most of last week's trading pushed rates slightly higher (i.e. short positions)
• Short positions were covered before the weekend, helping rates fall on Friday
• Short positions returned at the open today, pushing yields/rates higher
• Mortgages fared better than Treasuries, leaving rate sheets unchanged on average
• If you're not familiar with long vs short positions and how they're covered, read this.

Bond markets began the overnight session with a quick, but contained rally after the big oil meeting in Doha failed to produce the potential results.  Oil bulls were hoping for some word on supply reduction.  It didn't come, so oil jumped off a cliff.  

Markets were long since closed by the time the meeting ended, so there was a massive rush to sell oil and buy bonds right at the open.  This also made for an early, decisive bottom in prices and interest rates.  

Oil spent the rest of the day trudging back toward higher levels, though it never made it back to Friday's territory.  Bond traders who had closed out their short positions on Friday were happy to get back into them at the 8:20am CME open.  In other words, bond markets weakened early, pushing Treasury yields higher and MBS lower.

As is typically the case when it comes to big-picture volatility and market movement based on trader positioning, Treasuries experienced bigger moves than MBS.  By the end of the day, 10yr yields were 1.7bps higher while Fannie 3.0 MBS were within half a tick of being unchanged.  Most lenders' rate sheets are right in line with Friday's and there were no legitimate reprices (one was reported, but it clearly had no connection to market movement).